NCERT Exemplar Class 12 Biology Solutions Chapter 9 Strategies for Enhancement in Food Production

NCERT Exemplar Class 12 Biology Solutions Chapter 9 Strategies for Enhancement in Food Production-Multiple Choice Questions:

Question:1

The chances of contracting bird flu from a properly cooked (above 100°C) chicken and egg are:
a. very high
b. high
c. moderate

d. negligible

Answer:

The answer is the option (d) negligible
Explanation: When chicken is properly cooked, it helps in destroying the virus of bird flu.

Question:2

A group of animals which are related by descent and share many similarities are referred to as:
a. breed
b. race
c. variety
d. species

Answer:

The answer is the option (a) breed
Explanation: Race is a social group and has no biological meaning. Variety is used in the case of plants. Species is a proper taxonomic group whereas breed can be termed as a pseudo-taxonomic group within a species.

Question:3

Inbreeding is carried out in animal husbandry because it:
a. increases vigour
b. improves the breed
c. increases heterozygosity
d. increases homozygosity

Answer:

The answer is option (d) increases homozygosity
Explanation: Increased homozygosity helps in obtaining a pure line of breed.

Question:4

Sonalika and Kalyan Sona are varieties of:
a. wheat
b. rice
c. millet
d. tobacco

Answer:

The answer is the option (a) wheat

Question:5

Which one of the following is not a fungal disease?
a. Rust of wheat
b. Smut of Bajra
c. Black rot of crucifers
d. Red rot of sugarcane

Answer:

The answer is the option (c) Black rot of crucifers
Explanation: Black rot of crucifers is a bacterial disease.

Question:6

In virus-infected plants, the meristematic tissues in both apical and axillary buds are free of the virus because:
a. the dividing cells are virus-resistant
b. meristems have anti-viral compounds
c. the cell division of meristems is faster than the rate of viral multiplication
d. Viruses cannot multiply within the meristem cell (s).

Answer:

The answer is option (c) the cell division of meristems is faster than the rate of viral multiplication
Explanation: Meristematic cells are not affected by viruses because of the faster rate of multiplication.

Question:7

Several South Indian states raise 2-3 crops of rice annually. The agronomic feature that makes this possible is because of
a. shorter rice plants
b. better irrigation facilities
c. early yielding rice variety
d. disease-resistant rice variety

Answer:

The answer is the option (c) early yielding rice variety
Explanation: (c) early yielding rice variety

Question:8

Which one of the following combinations would a sugarcane farmer look for in the sugarcane crop?
a. Thick stem, long internodes, high sugar content and disease-resistant
b. Thick stem, high sugar content and profuse flowering
c. Thick stem, short internodes, high sugar content, disease-resistant
d. Thick stem, low sugar, content, disease-resistant

Answer:

The answer is the option (a) Thick stem, long internodes, high sugar content and disease-resistant
Explanation:(a) Thick stem, long internodes, high sugar content and disease resistant

Question:9

Fungicides and antibiotics are chemicals that:
a. enhance yield and disease resistance
b. kill pathogenic fungi and bacteria, respectively
c. kill all pathogenic microbes
d. kill pathogenic bacteria and fungi respectively.

Answer:

The answer is option (b) kills pathogenic fungi and bacteria, respectively
Explanation: (b) kill pathogenic fungi and bacteria, respectively

Question:10

Use of certain chemicals and radiation to change the base sequences of genes of crop plants are termed:
a. recombinant DNA technology
b. transgenic mechanism
c. mutation breeding
d. gene therapy.

Answer:

The answer is the option (c) mutation breeding
Explanation: Changing the base sequence of genes results in mutation.

Question:11

The scientific process by which crop plants are enriched with certain desirable nutrients are called:
a. crop protection
b. breeding
c. bio-fortification
d. bio-remediation

Answer:

The answer is the option (c) bio-fortification
Explanation: The term ‘fortification’ means augmentation of something.

Question:12

The term ‘totipotency’ refers to the capacity of a:
a. cell to generate whole plant
b. bud to generate whole plant
c. seed to germinate
d. cell to enlarge in size

Answer:

The answer is the option (a) cell to generate the whole plant

Question:13

Given below are a few statements regarding somatic hybridization. Choose the correct statements.
(i) protoplasts of different cells of the same plant are fused
(ii) protoplasts from cells of different species can be fused
(iii) treatment of cells with cellulase and pectinase is mandatory
(iv) the hybrid protoplast contains characters of only one parental protoplast.
a. (i) and (iii)
b. (i) and (ii)
c. (i) and (iv)
d. (ii) and (iii)

Answer:

The answer is the option (d) (ii) and (iii)

Question:14

An explant is:
a. dead plant
b. part of the plant
c. part of the plant used in tissue culture
d. part of the plant that expresses a specific gene

Answer:

The answer is the option (c) part of the plant used in tissue culture
Explanation: Explant is used for growing a whole new plant

Question:15

The biggest constraint of plant breeding is:
a. availability of desirable genes in the crop and its wild relatives
b. infrastructure
c. trained manpower
d. transfer of genes from unrelated sources.

Answer:

The answer is the option (a) availability of desirable genes in the crop and its wild relatives
Explanation: There is enough infrastructure available for plant breeding and there is no dearth of the trained workforce because of thousands of years of experience in farming.

Question:16

Lysine and tryptophan are:
a. proteins
b. non-essential amino acids
c. essential amino acids
d. aromatic amino acids.

Answer:

The answer is the option (c) essential amino acids

Question:17

Micro-propagation is:
a. propagation of microbes in vitro
b. propagation of plants in vitro
c. propagation of cells in vitro
d. growing plants on a smaller scale

Answer:

The answer is the option (b) propagation of plants in vitro
Explanation: A smaller scale can mean a small flowerpot, so option ‘d’ is incorrect. Microbes and cells are small enough to be easily grown in vitro and hence options a and c are incorrect.

Question:18

Protoplast is:
a. another name for protoplasm
b. an animal cell
c. a plant cell without a cell wall
d. a plant cell

Answer:

The answer is option (c) a plant cell without a cell wall

Question:19

To isolate protoplast, one needs:
a. pectinase
b. cellulase
c. both pectinase and cellulase
d. chitinase

Answer:

The answer is option (c) both pectinase and cellulase
Explanation: These are needed to dissolve the cell wall.

Question:20

Which one of the following is a marine fish:
a. Rohu
b. Hilsa
c. Catla
d. Common Carp

Answer:

The answer is the option (b) Hilsa
Explanation: Rohu, Catla and Common carp are freshwater fish.

Question:21

Which one of the following products of apiculture is used in cosmetics and polishes:
a. honey
b. propolis
c. wax
d. Royal jelly

Answer:

The answer is the option (c) wax

Question:22

More than 70 per cent of the livestock population is found in:
a. Denmark
b. India
c. China
d. India and China

Answer:

The answer is the option (d) India and China.

Question:23

The agriculture sector of India employs about:
a. 50 per cent of the population
b. 70 per cent of the population
c. 30 per cent of the population
d. 60 per cent of the population

Answer:

The answer is option (d) 60 per cent of the population.

Question:24

33 per cent of India’s Gross Domestic Product comes from
a. Industry
b. Agriculture
c. Export
d. Small-scale cottage industries

Answer:

The answer is the option (b) Agriculture

Question:25

A collection of all the alleles of all the genes of a crop plant is called:
a. germplasm collection
b. protoplasm collection
c. herbarium
d. somaclonal collection

Answer:

The answer is the option (a) germplasm collection

NCERT Exemplar Class 12 Biology Solutions Chapter 9 Strategies for Enhancement in Food Production- Very Short Answer Type Questions:

Question:1

Millions of chickens were killed in West Bengal, Assam, Orissa and Maharashtra recently. What was the reason?

Answer:

This was done because of the bird flu scare.

Question:2

Can gamma rays used for crop improvement programmes prove to be harmful to health? Discuss.

Answer:

This method has been used for producing moong variety which is resistant to yellow mosaic virus and powdery mildew. This is good evidence that the use of Gamma rays for crop improvement is not harmful to health.

Question:3

In animal husbandry, if two closely related animals are mated for a few generations, it results in loss of fertility and vigour. Why is this so?

Answer:

Inbreeding for many generations leads to inbreeding depression, which in turn causes loss of fertility and vigour.

Question:4

In the area of plant breeding, it is important not only to preserve the seeds of the variety being cultivated but also to preserve all its wild relatives. Explain with a suitable example.

Answer:

Preservation of the seeds of the cultivated variety and its wild varieties helps in making a good germplasm collection. Selective breeding of plants has produced many high-yielding and disease-resistant varieties of wheat, rice and maize. A better germplasm collection makes this possible.

Question:5

Name a man-made cereal. Trace how it was developed, and where is it used.

Answer:

Triticale is the first man-made cereal. It is a hybrid of wheat and rye. It was first bred in the laboratory in the late nineteenth century in Scotland and Sweden. It combines the yield potential and grain quality of wheat and the resistance qualities of rye. It is mainly used as fodder.

Question:6

Fill in the blanks

Answer:

I: Cellulase, II: Somatic hybridization, III: Tomato and potato, IV: Somatic hybrid

Question:7

A few statements are given below, followed by a set of terms in a box. Pick the correct term and write it against the appropriate statement
a. Mating of closely related individuals within the same breed
b. Mating of animals of the same breed but having no common ancestors on either side for 4-6 generations
c. Mating of animals of two different species
d. Breeding of animals belonging to different breeds
(i) Crossbreeding, (ii) Inter-specific hybridization, (iii) Outbreeding, (iv) Outcrossing, (v) Inbreeding

Answer:

(a) → (v)
(b) →(iv)
(c) →(ii)
(d) →(i)

Question:8

What is meant by ‘hidden hunger’?

Answer:

Many people are able to get good which contains only carbohydrates. These people do not get other nutrients, like protein, vitamins and minerals. This condition is called ‘hidden hunger’.

Question:9

Why are plants obtained by protoplast culture called somatic hybrids?

Answer:

Protoplast culture involves the fusion of two protoplasts from different plants. This is then allowed to produce a plant which has desirable characteristics from both plants. Since somatic cells are used for this purpose, hence such plants are called somatic hybrids.

Question:10

What is protoplast fusion?

Answer:

When protoplast from two plants is fused; this is called protoplast fusion. It is made possible by first dissolving the cellulose by a suitable enzyme.

Question:11

Why is it easier to culture meristems compared to permanent tissues?

Answer:

Cells of meristem have the capability of cell division while cells of permanent tissues do not have this capacity. Hence, it is easier to culture meristems as compared to permanent tissues.

Question:12

Why are proteins synthesized from Spirulina called single-cell proteins?

Answer:

Spirulina is a unicellular organism. Hence, a protein synthesized by it is called a single-cell protein.

Question:13

A person who is allergic to pulses was advised to take a capsule of Spirulina daily. Give the reasons for the advice.

Answer:

Spirulina is a good source of protein, which contains all the essential amino acids. The protein content of Spirulina is much higher than the pulses. Hence, it can be a better source of protein; especially for those who are allergic to pulses.

Question:14

What is aquaculture? Give an example of an animal that can be multiplied by aquaculture.

Answer:

Framing of aquatic animals and plants is called aquaculture. Pisciculture is a part of aquaculture. A prawn can be multiplied by aquaculture.

Question:15

What are the duties of a veterinary doctor in the management of a poultry farm?

Answer:

A veterinary doctor has the following duties in the management of a poultry farm:
(a) Regular inspection to ensure a disease-free environment.
(b) Ensure proper diet for the poultry.
(c) Ensure clean and hygienic enclosures.

Question:16

Would it be wrong to call plants obtained through micro-propagation as ‘clones’? Comment.

Answer:

It depends on the source of the gene pool. If a plant is produced from a single plant through micro-propagation, then it will be a clone. If a plant is produced after combining genes from more than one plant, then it cannot be a clone.

Question:17

How is a somatic hybrid different from a hybrid?

Answer:

A somatic hybrid is made from somatic cells, while a conventional hybrid is the result of fusion of gametes. Sexual reproduction is necessary to produce a conventional hybrid but is not necessary to produce a somatic hybrid.

Question:18

What is emasculation? Why and when is it done?

Answer:

The removal of anthers in a flower is called emasculation. This is done by cutting off the anthers with scissors or any other suitable tool.

Question:19

Discuss the two main limitations of a plant hybridization programme.

Answer:

Two main limitations of the plant hybridization programme are given below:
(a) Collection of germplasm: Cultivators and agricultural scientists need to have seeds of currently cultivated varieties as well as from wild varieties. This can prove to be a tedious process.
(b) Selection and Testing: A hybrid variety needs to be tested for all possible environmental factors; like climate, soil type, flood, drought, etc. before being released for real-life production. This is also a time-consuming process.

Question:20

Interspecific crosses are rare in nature and intergeneric crosses almost unknown. Why?

Answer:

Interbreeding is a major criterion for members of any species. If two individuals cannot breed, they cannot be termed as belonging to the same species. Hence, interspecific crosses are rare in nature. The same logic applies to intergeneric crosses.
The main reason lies in the difference in the number of chromosomes in the cells of different organisms. Due to this, a viable zygote cannot be formed by two gametes having different numbers of chromosomes. But artificial hybridization is being frequently used to produce interspecific and intergeneric crosses; especially for producing better varieties of plants.

Question:21

Differentiate between pisciculture and aquaculture.

Answer:

Pisciculture

1. Involves rearing and catching fish and other aquatic animals for food.
2. Plants do not come under this.

Aquaculture

1. Involves farming of all useful aquatic plants and animals.
2. Plants do come under this.

Question:22

Give two important contributions of Dr M. S. Swaminathan.

Answer:

Two important contributions of Dr M. S. Swaminathan are as follows:
(a) Was instrumental in initiating the Green Revolution in India
(b) Began the programme called “Lab to Land” to ensure food security in India.

Question:23

The term ‘desirable trait’ can mean different things for different plants. Justify the statement with suitable examples.

Answer:

This can be illustrated with the help of the following examples:
(a) The thick and tall stem can be a desirable trait in sugarcane, but the dwarf stem is desirable in rice plants.
(b) More leaves are desirable in spinach, but this may not be the case in the mustard plant.

NCERT Exemplar Class 12 Biology Solutions Chapter 9 Strategies for Enhancement in Food Production- Short Answer Type Questions:

Question:1

You are planning to set up a Dairy Farm. Describe the various aspects you would consider before you start the venture.

Answer:

The following aspects need to be considered before starting the venture:
(i) Selection of Good Breed: The breed should be able to give a high yield of milk. It should be resistant to various diseases.
(ii) Construction of cattle shed: The cattle shed should be properly ventilated and should get plenty of natural light. The slope of the floor should allow for quick drainage of water.
(iii) Availability of fodder: Fodder should contain bulk as well as necessary nutrients.
(iv) Availability of veterinary doctor: A veterinary doctor should be available nearby so that proper medical care for cattle can be ensured at the time of need.

Question:2

It is said that diseases are spreading faster due to globalization and increased movement of people. Justify the statement by taking the example of the H5N1 virus.

Answer:

H5N1 virus is a subtype of influenza virus. Influenza caused by this virus is called avian influenza or bird flu. This disease first erupted in Southeast Asia and then spread to other parts of the world. The spread of this disease to many other countries was mainly possible because of ithe nternational trade of chickens.
This shows that globalization and increased movement of people have facilitated in the faster spread of diseases.

Question:3

Explain the concept of the Blue Revolution.

Answer:

Blue Revolution is similar to Green Revolution but is more related to aquaculture. Aquaculture has been practised in many parts of the world since time immemorial, but traditional methods have failed to improve productivity to keep the pace of growing demand. The use of scientific methods to improve the variety of fish products, better management of aquaculture products, improved catch, etc. come under the Blue Revolution.
A blue revolution has helped in improving fish production in many parts of India. It has also helped in improving the income of thousands of fishermen in our country.

Question:4

A farmer was facing the problem of low yield from his farm. He was advised to keep a beehive in the vicinity. Why? How would the beehive help in enhancing yield?

Answer:

It appears that the low yield from the farm was because of the absence of sufficient pollinators. We know that pollination is important for seed production in many crops. Insects are important agents of pollination and bees pollinate many plant species. Keeping a beehive near the farm will help in the proper pollination of the crop during the flowering stage. This will eventually help in improving the farm yield. Moreover, it will also augment the farmer’s income by selling honey and beeswax.

Question:5

Lifestyle diseases are increasing alarmingly in India. We are also dealing with large-scale malnutrition in the population. Is there any method by which we can address both of these problems together?

Answer:

Lack of a balanced diet is the root cause of all lifestyle diseases and malnutrition. A person who takes a carbohydrate and fat-rich diet and ignores protein, vitamins and minerals is more likely to suffer from lifestyle diseases. Malnutrition happens because of the lack of most of the nutrients in the diet. Ensuring the availability of all kinds of food (in terms of available nutrients) is one way of tackling these problems. Another method could be by using biofortification to improve the availability of all the nutrients in food.

Question:6

How can we improve the success rate of fertilization during artificial insemination in animal husbandry programmes?

Answer:

MOET is a good method to follow to improve the success rate of fertilization during artificial insemination in animal husbandry. MOET stands for Multiple Ovulation Embryo Transfer Technology. Under this programme, a cow is administered a hormone which has a similar activity to FSH (Follicle follicle-stimulating hormone). This causes superovulation in the cow, and the cow produces six to eight eggs in an ovulation cycle instead of the normal count of one egg per ovulation cycle. After that, that animal is artificially inseminated. Zygotes are allowed to develop up to 8 to 32 cell stages. Then the embryo is transplanted to a surrogate mother so that a healthy calf can be produced. This method ensures a higher success rate in artificial insemination.

Question:7

What is meant by germplasm collection? What are its benefits?

Answer:

Preservation of the seeds of the cultivated variety and its wild varieties helps in making a good germplasm collection. Following are the benefits of germplasm collection.
(a) This helps in preparing a large pool of desirable characters in a plant species.
(b) This helps in the proper selection of suitable traits during a hybridization programme.
(c) This helps in combining the best of cultivated and wild varieties of plants.

Question:8

Name the improved characteristics of wheat that helped India to achieve a green revolution.

Answer:

Following were the improved characteristics of wheat that helped India to achieve the Green Revolution:
(a) Semi-dwarf Plants: Dwarf plants mean that most of the resources are utilized in producing a greater number of grains in the plant.
(b) High Yield: The new varieties could give higher yield; in terms of per acre production of wheat.
(c) Disease Resistance: The new plants were resistant to many diseases, which used to trouble the traditional wheat varieties.
(d) Quick Yield: The new varieties took a short time duration for the maturation of crops.

Question:9

Suggest some of the features of plants that will prevent insect and pest infestation.

Answer:

Some of the features of plants that prevent insects and pest infestation are as follows:
(a) Hairy leaves are supposed to resist pest attack, e.g. jassids do not attack cotton, and leaf beetles do not attack wheat.
(b) The solid stem of wheat makes it resistant to stem sawfly.
(c) Nectar-less cotton varieties do not attract bollworms.
(d) High aspartic acid, low nitrogen and sugar content in maize lead to resistance in maize stem borers.

Question:10

It is easier to culture plant cells in vitro as compared to animal cells. Why?

Answer:

It is easier to culture plant cells in vitro as compared to animal cells. The following are the reasons for this:
(a) Meristem is present in a plant, and cells of meristem always undergo cell division. In animals, most of the cells stop dividing after a certain age. The main purpose of cell division in an adult animal is to repair.
(b) Plant tissues dedifferentiate in case of need, but animal tissues do not show such property.

Question:11

The culture medium (nutrient medium) can be referred to as a 'highly enriched laboratory soil'. Justify the statement.

Answer:

Soil is the reservoir of water and plant nutrients. Similarly, a culture medium or nutrient medium is the reservoir of water and plant nutrients for plants being grown on a culture medium. Soil may have higher or lower nutrient content, and many nutrients may be missing. But in the culture medium, all the essential nutrients are supplied as needed. Hence, the culture medium is richer in terms of nutrients for plants. Due to these reasons, the culture medium can be called a highly enriched laboratory soil.

Question:12

Is there any relationship between dedifferentiation and the higher degree of success achieved in plant tissue culture experiments?

Answer:

We know that cells of meristematic tissue undergo differentiation and lose their capability to divide in order to form permanent tissue. But plants have this special ability to convert permanent tissue into meristematic tissue if the need arises. This phenomenon is called dedifferentiation. Because of their ability to undergo dedifferentiation, many plant tissues can once again undergo cell division to produce new parts. So, a higher degree of success is achieved in plant tissue experiments because of this ability of plant tissues.

Question:13

“Give me a living cell of any plant, and I will give you a thousand plants of the same type” Is this only a slogan or is it scientifically possible? Write your comments and justify them.

Answer:

We know that tissue culture has made it possible to produce a new plant from any part of a plant. A small part of a plant which is utilized for growing a plant through tissue culture is called explants. So, theoretically; a single cell from a plant can be utilized to produce a thousand plants of the same species. Thus, “Give me a living cell of any plant, and I will give you a thousand plants of the same type” is scientifically possible.

Question:14

What is the difference between a breed and a species? Give an example for each category.

Answer:

A breed is a specific group of domestic animals which are homogenous in appearance.
Breed
(i) Animals of the same breed look similar.
(ii)A species can include more than one breed.

1. Example: Jersey and Sahiwal are breeds of cow.

SPECIES

1. Animals of a species may not look similar
2. A species is at a higher level compared to a breed.
3. Example: Bos indicus is a species of cow.

Question:15

Plants raised through tissue cultures are clones of the ‘parent’ plant. Discuss the utility of these plants.

Answer:

Plants raised through tissue culture have the following benefits:
(a) A large number of clones can be produced in a shorter time span.
(b) Desirable characters can be easily selected through tissue culture.
(c) Somatic hybrids can be prepared using this method.
(d) High-yield varieties can be produced through tissue culture.
(e) A healthy plant can be recovered from a diseased plant.

Question:16

Discuss the importance of testing new plant varieties in a geographically vast country like India.

Answer:

India is a large country. It has different soil types and varying climatic conditions in different parts. For a crop variety to be successful all over India should be able to show good results in each and every part of the country. Due to this, testing of new plant varieties is done in simulated conditions which mimic the diverse climatic conditions and soil types in the country. If a crop variety passes this test, then only it is considered suitable for introduction in the market.

Question:17

Define the term ‘stress’ for plants. Discuss briefly the two types of stress encountered by plants.

Answer:

A plant has to constantly interact with various biotic and abiotic factors. These factors may put stress on a plant. Two types of stress which a plant often encounters are as follows:
(a) Environmental Stress: Environmental stress is produced by unfavourable conditions; like salinity, drought, extreme temperatures, etc. Many crop plants are unable to survive extreme saline conditions or drought or extreme temperatures.
(b) Biotic Stress: Biotic stresses come in the form of insects and pests. Weeds also represent biotic stress for plants. While pests and insects do direct harm to the plants, weeds do so by competing for available resources, like sunlight, nutrients and water.

Question:18

Discuss natural selection and artificial selection. What are the implications of the latter on the process of evolution?

Answer:

Natural Selection: As implied by the name, nature selects organisms with suitable traits. Organisms which are better equipped to survive in the changed environmental conditions are able to produce more progenies and continue their lineage.
Artificial Selection: Artificial selection is brought about by humans: Human beings have been doing selective breeding of various plants and animals to obtain benefits from them. Artificial selection too has an important role to play in the process of evolution. Many plant varieties or animal breeds have come into origin because of artificial selection. Let us take the example of wild cabbage which has been subjected to artificial selection for a long time. Cauliflower, broccoli, cabbage, etc. are the results of selective breeding in wild cabbage.

Question:19

Discuss briefly how pure lines are created in animal husbandry.

Answer:

Pure lines are created using in-breeding. When breeding is done with closely related individuals, it is called inbreeding. A superior male and a superior female are selected for this purpose, and they are mated. From the next generation, superior males and females are selected to continue the process. This is continued for 4 to 5 generations to achieve pure line. Inbreeding increases homozygosity and thus enables to obtaining of pure lines. However, inbreeding depression is a major problem with this method.

Question:20

What are the physical barriers of a cell in the protoplast fusion experiment? How are the barriers overcome?

Answer:

The cell wall is the physical barrier which can prevent protoplast fusion. The cell wall, which is made up of cellulose, is dissolved with the help of the enzyme cellulase. The fusion of protoplast is then carried out by electrical and chemical processes.

Question:21

Give a few examples of biofortified crops. What benefits do they offer to society?

Answer:

Examples of biofortified crops are golden rice (fortified with vitamin A, iron and zinc, sweet potato (fortified with beta carotene), vitamin A-enriched carrot, iron-enriched bitter gourd, etc.
Benefits of Biofortified Crops: Biofortified crops promise many benefits for society. These are especially useful for people who may be suffering from ‘hidden hunger’. Many poor people get just enough food to beat the hunger. But they don’t get most of the nutrients in their food. As a result, these people often suffer from malnourishment and related diseases. Cases of anaemia, night blindness, rickets, etc. are quite common among poor people. These problems can be overcome by providing biofortified food to these people.

NCERT Exemplar Class 12 Biology Solutions Chapter 9 Strategies for Enhancement in Food Production- Long Answer Type Questions:

Question:1

You are a Botanist working in the area of plant breeding. Describe the various steps that you will undertake to release a new variety.

Answer:

The following steps need to be taken to release a new variety of crops:
(a) Collection of Variability: Genetic variability is the most important for any breeding programme. For this, seeds of present cultivated varieties are collected along with seeds of wild varieties of plants. Currentl,y cultivated varieties would give various desirable characteristics; from the perspective of better yield. Wild varieties will give desirable characteristics; from the perspective of resistance to various stresses.
(b) Selection and Evaluation of Parents: Germplasm is evaluated to make a list of desirable characters. Varieties, which fulfil most of the criteria, are then selected to produce pure lines.
(c) Cross-Hybridization Among Selected Parents: After the above step, cross-hybridization of selected parents is carried out. The success rate of cross-hybridization is quite low because very few individuals in the next generation may show all the desirable characteristics. Hence, this is a time-consuming process, as well. Only one in a few hundreds or thousands of crosses show the desirable combination.
(d) Selection and Testing of Superior Recombinants: Crosses with the desirable combination are selected and are self-pollinated for several generations to produce pure lines.
(e) Testing and Release: Agriculture involves various applications and is done in different kinds of climates and in different soil types. This is especially true for a vast country like India. Once a pure line of a plant with desirable characteristics is obtained, it is grown in various simulated conditions to assess its viability in real life. Once a variety passes this test, it is ready for release in the market.

Question:2

(a) The shift from grain to meat diets creates more demand for cereals. Why?

(b) A 250 kg cow produces 200 g of protein per day, but 250 g of Methylophillusmethylotrophus can produce 25 tonnes of protein Name this emerging area of research. Explain its benefits.

Answer:

(a) It is a known fact that 90% of the biomass consumed by an organism at a particular trophic level is utilized for its own need and just 10% is available for the organism at the next trophic level. So, to produce 1 kg of meat one needs to spend 3 to 10 kg of grains on the cattle. This shows that a shift from grain to meat diets creates more demand for cereals.
(b) This emerging area of research is called single-cell proteins (SCP). Single-cell protein is formed during the decomposition of organic materials by bacteria, fungi and algae. Single-cell protein provides a very high protein content. The following are the benefits of this process:
i) A higher protein yield per unit of biomass.
ii) Better utilization of solar energy per unit area.
iii) This is an environment-friendly process.
iv) Land requirement is low.
v) Production is independent of seasonal or climatic variations.
vi) This may help in tackling the problem of food security.

Question:3

What are the advantages of tissue culture methods over the conventional method of plant breeding in crop improvement programmes?

Answer:

Tissue culture has the following advantages over the conventional method of plant breeding in crop improvement programmes:

• The new plant can be produced by using any part of the parent plant. A small tissue can be used to produce hundreds of plants.
• Producing a new generation takes a short time span, and hence this process is faster than the conventional method.
• Offspring are clones of parent plants, so producing pure line is less time-consuming. One need not wait for 4 to 5 generations to achieve this.
• The land requirement is nil for this method. So, this method is less resource-intensive than the conventional method.
• Healthy plants can be recovered from diseased plants by utilizing this method. Thus,

producing disease-resistant plants is quite easy with this method.

Question:4

'Modern methods of breeding animals and plants can alleviate the global food shortage'. Comment on the statement and give suitable examples.

Answer:

This is a correct statement that modern methods of breeding animals and plants can alleviate the global food shortage. If we compare the status of food security during World War days with the current situation; it can be said that the food security situation is much better in modern times than it was earlier. This could have been possible because of better varieties of plants and cattle. Food processing and food preservation technologies have also been responsible for this, but their role was at best at the augmentation level.
Following are some of the examples, which illustrate this; Before the 1950s, India had to depend on wheat imports from the USA to meet its needs. After the Green Revolution, many better varieties of wheat were introduced, which helped increase the farm output. From 1960 to 2000, wheat production increased from 11 million tonnes to 75 million tonnes. In the same period, rice production increased from 35 million tonnes to 89 million tonnes. At present, India is not only a sufficient food nation but also exports a major chunk of its food grain production.
The introduction of hybrid breeds of cows made India a leading nation in terms of milk production.
Better practices in poultry farming have enabled the majority of Indians to get access to chicken and eggs as part of a regular diet.
Major developments have taken place in the field of pisciculture as well. This has helped in improving the income of fishermen and has also improved the availability of fish throughout the country.

Question:5

Does apiculture offer multiple advantages to farmers? List its advantages if it is located near a place of commercial flower cultivation.

Answer:

Apiculture indeed offers multiple advantages to farmers. The following are the advantages of having an apiary near a place of commercial flower cultivation:
(a) Bees will get plenty of flowers as a source of nectar. This will help them in preparing a larger quantity of honey. Beeswax production will also increase significantly.
(b) Bees are important pollinations. They will help in improving flower production. This will help the horticulturist to increase his income by selling flowers.
(c) This will also help in improving the availability of flowers for the perfume industry.
(d) The essential oils from many flowers are used in many medicinal products. So, better flower cultivation will support this activity as well.

Question:6

(a) Mutations are beneficial for plant breeding. Taking an example, justify the statement. (b) Discuss briefly the technology that made us self-sufficient in food production.

Answer:

(a) Changes which can be induced by changing the base sequence in the gene are called a mutation. Mutation can be induced in plants by using suitable technology, like Gamma radiation. Many disease-resistant varieties of plants can be obtained through mutational breeding. For example, resistance to yellow mosaic virus and powdery mildew could be obtained in mung beans through mutational breeding.
(b) Plant breeding has made us self-sufficient in food production. Many techniques are employed for plant breeding to produce high-yielding and disease-resistant varieties of various crops. In India, better varieties of rice, wheat, maize, etc. could be produced because of various methods of plant breeding.
Many technologies which were existent but not being used on a large scale could be used by more farmers because of the Green Revolution. Irrigation, pesticides and synthetic fertilizers were among such technologies.
Irrigation Projects: The Green Revolution could not be successful without the proper implementation of large irrigation projects. Many multipurpose dams were built to feed irrigation canals. Punjab is a good example of a state, which has benefited from a good network of canals.
Pesticides: Pesticides were used more vigorously during the Green Revolution. This helped in improving farm yield significantly.
Synthetic Fertilizers: While manure is very good, it does not show as dramatic results as synthetic fertilizers. The government opened many fertilizer factories to meet the demand. Farmers were given subsidies on fertilizers so that farm production could be improved.

Question:7

Discuss how the property of plant cell totipotency has been utilized for plant propagation and improvement.

Answer:

During the 1950s, scientists learned that a whole plant could be generated from an explant. Any part of a plant grown in a test tube under sterile conditions by using a special nutrient medium is called an explant.
The ability of a cell to produce a whole organism is called totipotency. By using this property, it is possible to produce a large number of plants in a short duration. The nutrient medium for this purpose must contain a source of carbon, like sucrose. It should also contain inorganic salts, vitamins, amino acids, and plant hormones.
Plants grown through this method are clones of the parent plant. They are often called somaclones. Many desirable characteristics can be introduced in the progeny by using this method and a combination of genetic engineering. Healthy plants can be grown from a diseased plant by using this method. Virus-free plants can be easily produced by using this method. This method has been employed to produce plants of banana, sugarcane, potato, etc.

Question:8

What are three options to increase food production? Discuss each giving the salient features, merits and demerits.

Answer:

Food production can be increased by the following methods:
(a) By introducing better crop varieties: This can be done by selective breeding of plants to include desirable characteristics in a particular plant.
Merits: Many new varieties of wheat, rice, maize, etc. had been introduced. This helped significantly improve wheat and rice production after the implementation of the Green Revolution in India. Per acre yield increased because of high-yielding and disease-resistant varieties of plants.
Demerits: Sometimes, selective breeding can produce some obnoxious weed which can be difficult to get rid of. Some mutations in plants can be highly harmful to the human population.
(b) by improving irrigation facilities: Water is especially important for plants and crops to need a lot of water to grow properly. For example, a rice plant needs so much water that it is kept submerged for most of the time of the cropping season.
Merits: Better irrigation facilities have helped in improving crop production in many states. Farmers in many states (like Punjab and Haryana) became rich because of better irrigation facilities.
Demerits: Intensive irrigation leads to overexploitation of water resources. At many places, the water table has gone down drastically because of intensive irrigation. This is creating a shortage of drinking water in many places. Constructing dams also adversely affects the environment.
(c) By using synthetic fertilizers: Plants take up many minerals from the soil. As a result, the soil is sapped up of most of the nutrients after a couple of farming cycles. Some method needs to be applied so that soil can replenish lost nutrients. Adding synthetic fertilizers is the fastest way of achieving this.
Merits: Synthetic fertilizers help in quickly replenishing soil nutrients.
Demerits: Synthetic fertilizers leave many harmful chemicals in the soil. This leads to groundwater pollution. This also leads to the accumulation of harmful substances in the human body because of bioaccumulation